Silicone rubber particle and water dispersion of silicone rubber particle
Patent Information
- Application Number
- JP2022173374
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-10-28
- Publication Date
- 2025-12-23
- Estimated Expiration
- 2042-10-28
Abstract
Description
[Technical field]
[0001] The present invention relates to silicone rubber particles having high strength and elongation, and to an aqueous dispersion of said silicone rubber particles. [Background technology]
[0002] Silicone rubber particles are used as stress relaxation agents for resins, light diffusing agents for resins, feel improvers for cosmetics, matting agents for paints and coatings, feel improvers, slip improvers, and the like. Generally, silicone rubber particles do not contain fillers such as silica, which results in low rubber strength and small elongation. When used in paints and coatings, the silicone rubber particles contained in the rubber can break due to the load exerted when the coating is subjected to friction.
[0003] Patent Document 1 proposes high-strength silicone rubber particles containing silica. The particles are produced by mixing silica into a curable liquid silicone composition, dispersing (emulsifying) the mixture in water containing a surfactant, and then carrying out a curing reaction. In this method, the resulting emulsion is less stable, and some particles may aggregate. In addition, it is difficult to increase the silica content in the particles, making it difficult to produce rubber particles with higher strength. Patent Document 2 proposes organosiloxane resin-containing silicone rubber particles made from diorganopolysiloxane having alkenyl groups, organopolysiloxane resin, and organohydrogenpolysiloxane having silicon-bonded hydrogen as raw materials. However, the silicone rubber particles described in Patent Document 2 have low rubber strength and elongation. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] Japanese Patent Application Publication No. 4-168117 [Patent Document 2] JP 2000-204258 A
[0005] The present invention has been made in consideration of the above circumstances, and has as its object to provide silicone rubber particles and an aqueous dispersion of silicone rubber particles that have high strength and elongation and a small amount of agglomerated particles. Summary of the Invention [Means for solving the problem]
[0006] As a result of intensive research into achieving the above-mentioned object, the present inventors have discovered that the above-mentioned object can be achieved by using a specific amount of organopolysiloxane having alkenyl groups in organopolysiloxane resin-containing silicone rubber particles made from raw materials such as a diorganopolysiloxane having alkenyl groups, an organopolysiloxane resin having alkenyl groups, and an organohydrogenpolysiloxane having silicon-bonded hydrogen, and have thus completed the present invention.
[0007] That is, the present invention provides the following silicone rubber particles and aqueous dispersion of silicone rubber particles. The silicone rubber particles are spherical and have a volume average particle size of 0.5 to 50 μm, and are an addition reaction product of a curable liquid silicone composition comprising the following components (A-1), (A-2) and (A-3): (A-1) a diorganopolysiloxane having two or more alkenyl groups per molecule, the amount of alkenyl groups being 0.0025 to 0.034 mol / 100 g; (A-2)R 1 3SiO 1 / 2 Units and SiO 4 / 2 Contains the unit SiO 4 / 2 R for units 1 3SiO 1 / 2 an organopolysiloxane resin having a molar ratio of units of 0.60 to 1.7 and an alkenyl group content of 0.001 mol / 100 g or more; (In the above formula, R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms not containing an alkenyl group, or an alkenyl group having 2 to 6 carbon atoms, 1at least one of which is an alkenyl group, and (A-3) Organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms (referred to as SiH groups) per molecule, with the amount of SiH groups being 0.030 to 1.30 mol / 100 g. The amount of the component (A-2) is 1.0 to 65 parts by mass per 100 parts by mass of the total of the components (A-1), (A-2) and (A-3).
[0008] The present invention further provides the silicone rubber particles, wherein the silicone rubber particles are made of silicone rubber having, for a 1 mm thick rubber sheet heat-treated at 150°C for 30 minutes, an elongation at break of a dumbbell-shaped No. 3 test piece according to the test method specified in JIS K 6251 of 20% or more, and a tensile strength at break of 1.0 MPa or more according to the test method specified in JIS K 6251.
[0009] Further, the present invention relates to (A) Silicone rubber particles according to claim 1 or 2: 100 parts by mass (B) a surfactant: 0.05 to 20 parts by mass, and (C) Water: 20~2,000 parts by mass The present invention provides an aqueous dispersion of the silicone rubber particles, comprising: Effect of the Invention
[0010] The silicone rubber particles of the present invention have high rubber strength and elongation. The silicone particles and aqueous dispersions containing the silicone particles are useful for paints and coatings that are subject to friction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] The present invention will be described in detail below. [Silicone rubber particles] The shape of the silicone rubber particles (A) of the present invention is spherical. In this specification, "spherical" means that the shape of the particles is not only a perfect sphere, but also a deformed sphere in which the ratio of the length of the longest axis to the length of the shortest axis (aspect ratio) is on average usually in the range of 1.0 to 4.0, preferably 1.0 to 2.0, more preferably 1.0 to 1.6, and even more preferably 1.0 to 1.4. The shape of the particles can be confirmed by observing the particles with an optical microscope, an electron microscope, or the like. It can also be measured by a particle shape analyzer using the dynamic image analysis method. The volume average particle diameter of the particles is 0.5 to 50 μm, preferably 1.0 to 30 μm, and more preferably 2.0 to 20 μm. The volume average particle diameter is measured by the Coulter counter method (electrical resistance method).
[0012] The silicone rubber of the silicone rubber particles (A) is an addition reaction product of a curable liquid silicone composition containing (A-1) a diorganopolysiloxane having two or more alkenyl groups in one molecule, (A-2) an organopolysiloxane resin having an alkenyl group, and (A-3) an organohydrogenpolysiloxane having two or more SiH groups in one molecule.
[0013] (A-1) The diorganopolysiloxane having two or more alkenyl groups in one molecule of the component has the following average composition formula (1) R 2 a R 3 b SiO (4-a-b) / 2 (1) It is represented by. In the formula, R 2 are each independently a monovalent hydrocarbon group having 1 to 30 carbon atoms that is unsubstituted or substituted and does not have an alkenyl group, and R 3 are each independently an alkenyl group having 2 to 8 carbon atoms, and a and b are positive numbers that satisfy 0 <a <3, 0 <b ≤ 3, and 0.1 ≤ a + b ≤ 3. One kind of the diorganopolysiloxane represented by the average composition formula (1) may be used alone or two or more kinds may be used in combination.
[0014] R 2is a monovalent hydrocarbon group having 1 to 30 carbon atoms, which may be unsubstituted or substituted, preferably a monovalent hydrocarbon group having 1 to 22 carbon atoms, more preferably 1 to 18 carbon atoms. R 2 Examples of R include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, decyl group, undecyl group, dodecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henicicosyl group, docosyl group, tricosyl group, tetracosyl group, triacontyl group; aryl groups such as phenyl group, tolyl group, naphthyl group; aralkyl groups such as benzyl group, phenethyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group; and hydrocarbon groups in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with atoms such as halogen atoms (fluorine atom, chlorine atom, bromine atom, iodine atom) and / or substituents such as acryloyloxy group, methacryloyloxy group, amino group, epoxy group, glycidoxy group, carboxyl group. It is preferable that 50 mol% or more of all R is a methyl group. 2 It is preferable that 50 mol% or more of all R is a methyl group. R 3 Examples of R include vinyl group, allyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, octenyl group, preferably vinyl group, allyl group and hexenyl group, more preferably vinyl group. a and b are preferably positive numbers satisfying 0 < a ≦ 2.295, 0.005 ≦ b ≦ 2.3, 0.5 ≦ a + b ≦ 2.3.
[0015] The silicone rubber particles of the present invention are characterized in that the amount of alkenyl groups in the (A-1) component is 0.0025 to 0.034 mol / 100g. If it is more than 0.034 mol / 100g, the strength and elongation of the resulting silicone rubber will be low. If it is less than 0.0025 mol / 100g, the viscosity will be high due to a structure with a high degree of polymerization, and the viscosity of the curable liquid silicone consisting of the (A-2) component and the (A-3) component will be high, making the emulsification described below difficult. It is preferably 0.0030 to 0.027 mol / 100g, more preferably 0.0035 to 0.020 mol / 100g.
[0016] The viscosity of component (A-1) at 25°C is 100,000mm 2 / s or less is preferable, and 50,000 mm 2 / s or less. Viscosity is 100,000mm 2 If the viscosity is higher than 150 mm / s, the viscosity of the curable liquid silicone composed of components (A-2) and (A-3) will be high, making the emulsification described below difficult. 2 At a degree of polymerization lower than 150 mm / s, the alkenyl content is unlikely to be 0.033 mol / 100 g or less. 2 / s or more is sufficient, especially 300 mm 2 / s or more. The structure of component (A-1) may be linear, cyclic, or branched, but is preferably linear or branched with fewer branch units. There are no particular restrictions on the bonding site of the alkenyl group, and it may be bonded to any silicon atom in the side chain or at the terminal of the molecule.
[0017] An example of the straight-chain structure is that represented by the following general formula (2). [ka] In the formula, R 2 , R 3is the same as above, c is a positive number of 10 to 1,500, preferably a positive number of 30 to 1000, more preferably a positive number of 50 to 800, and even more preferably a positive number of 80 to 800, d is 0 or a positive number of 50 or less, and e is 0, 1, 2, or 3, with the proviso that d and e are numbers that satisfy d+2×e≧2.
[0018] Examples of branched structures include R 2 SiO 3 / 2 Examples of the branched units include those represented by the following general formula (3). [ka] In the formula, R 2 , R 3 is the same as above, f is a positive number of 10 to 1,500, preferably a positive number of 30 to 1000, more preferably a positive number of 50 to 800, and even more preferably a positive number of 80 to 800, g is 0 or a positive number of 50 or less, h is a positive number of 1 to 10, and i is 0, 1, 2, or 3, with the proviso that g and i are numbers that satisfy g+i≧1.
[0019] SiO 4 / 2 An example of a structure branched by units is one represented by the following general formula (4). [ka] In the formula, R 2 , R 3 is the same as above, j is a positive number of 10 to 1,500, preferably a positive number of 30 to 1000, more preferably a positive number of 50 to 800, and even more preferably a positive number of 80 to 800, k is 0 or a positive number of 50 or less, l is a positive number of 1 to 5, and m is 0, 1, 2, or 3, with the proviso that k and m are numbers that satisfy k+m≧1.
[0020] The component (A-2) is R 1 3SiO 1 / 2 Units and SiO 4 / 2 It is an organopolysiloxane resin having alkenyl groups containing units. It is in a solid state at 25°C. In the formula, R 1are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms not containing an alkenyl group, or an alkenyl group having 2 to 8 carbon atoms. 1 At least one of the groups is an alkenyl group. One type of organopolysiloxane resin may be used alone, or two or more types may be used in combination.
[0021] The monovalent hydrocarbon group not having an alkenyl group has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, and more preferably 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group not having an alkenyl group include R 2 The groups exemplified for R 1 It is preferable that 50 mol % or more of them are methyl groups.
[0022] Examples of the alkenyl group having 2 to 8 carbon atoms include a vinyl group, an allyl group, a propenyl group, a butenyl group, a pentenyl group, and a hexenyl group, of which a vinyl group and an allyl group are preferred, and a vinyl group is more preferred.
[0023] In organopolysiloxane resin, R 1 3SiO 1 / 2 Unit (hereinafter referred to as M unit) and SiO 4 / 2 The molar ratio of units (hereinafter referred to as Q units), i.e. [moles of M units] / [moles of Q units], is 0.60 to 1.7, preferably 0.65 to 1.3, and more preferably 0.70 to 1.1.
[0024] The (A-2) component contains, in addition to the above M and Q units, (R 4 O)SiO 3 / 2 In the formula, R 4 are each independently a hydrogen atom or an unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms. (R 4 O)SiO 3 / 2 The units are derived from the raw material. 4 O groups undergo condensation reaction, but R groups do not react. 4 O groups may remain in the organopolysiloxane resin. Examples of unsubstituted monovalent hydrocarbon groups having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. (R 4 O)SiO 3 / 2 The content of the unit (called Q3 unit) is (R 4 O)SiO 3 / 2 Units and SiO 4 / 2 The unit of mole ratio [(R 4 O)SiO 3 / 2 [mol] / [SiO 4 / 2 In other words, [moles of Q3 units] / [moles of Q units] is preferably 0 to 0.50, more preferably 0.01 to 0.40, and even more preferably 0.02 to 0.30.
[0025] The component (A-2) is preferably R 2 O 3 to the extent that it does not impair its property of being a solid at 25°C and its solubility in the components (A-1) and (A-3) in the production of the silicone rubber particles (A) described below. 5 SiO 3 / 2 Units and / or R 6 2SiO 2 / 2 It is also possible to include units in the formula: 5 and R 6 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms. 5 SiO 3 / 2 Units (called T units) and R 6 2Si 2 / 2 The content of units (referred to as D units) is preferably such that [moles of T units and D units] / [moles of Q units] is 0.3 or less.
[0026] (A-2) component has an alkenyl group content of 0.001 mol / 100 g or more. If it is less than 0.001 mol / 100 g, the strength and elongation of the silicone rubber will be low. Preferably, it is 0.005 mol / 100 g or more, more preferably 0.01 mol / 100 g or more. The upper limit is not particularly limited, but if it is more than 2.0 mol / 100 g, the molar ratio of [moles of M unit] / [moles of Q unit] cannot be 1.7 or less, so it may be 0.8 mol / 100 g or less, particularly 0.50 mol / 100 g or less. The polystyrene-reduced weight average molecular weight of the (A-2) component by gel permeation chromatography is preferably 1,000 to 10,000, more preferably 2,000 to 8,000.
[0027] (A-3) component, the organohydrogenpolysiloxane having two or more SiH groups in one molecule, has the following average compositional formula (5) R 7 n H o SiO (4-n-0) / 2 (5) It is represented by. In the formula, R 7 are each independently a monovalent hydrocarbon group having 1 to 30 carbon atoms, unsubstituted or substituted, and having no alkenyl group. n and o are numbers satisfying 0 < n < 3, 0 < o ≤ 3, and 0.1 ≤ n + o ≤ 3. One kind of the organohydrogenpolysiloxane represented by the average compositional formula (5) may be used alone or two or more kinds may be used in combination.
[0028] R 7 has 1 to 30 carbon atoms, preferably 1 to 22, more preferably 1 to 18. R 7 is the monovalent hydrocarbon group exemplified for R 2 , and preferably 80 mol% or more of R 7 is a methyl group, more preferably 95% or more is a methyl group. n and o are preferably positive numbers satisfying 0 < n ≤ 2.295, 0.005 ≤ o ≤ 2.3, and 0.5 ≤ n + o ≤ 2.3.
[0029] The amount of SiH groups in the (A-3) component is 0.030 to 1.30 mol / 100g. If it is less than 0.030 mol / 100g, the strength and elongation of the silicone rubber will be reduced. If it is more than 1.30 mol / 100g, there is a risk that dispersed particles will aggregate in the aqueous dispersion of silicone rubber particles described below. It is preferably 0.050 to 1.10 mol / 100g, more preferably 0.10 to 0.90 mol / 100g.
[0030] The viscosity of component (A-3) at 25°C is 100,000mm 2 / s or less is preferable, and 10,000 mm 2 / s or less. Viscosity is 100,000mm 2 When the viscosity is less than 0.4 mm / s, it is particularly easy to obtain silicone microparticles having a narrow particle size distribution by the production method described below. 2 / s or more is sufficient, especially 2 mm 2 / s or more. The structure of component (A-3) may be linear, cyclic, or branched, with linear or branched being particularly preferred. There are no particular limitations on the bonding sites of the hydrogen atoms bonded to silicon atoms, and they may be bonded to silicon atoms in either the side chains or the terminals of the molecule.
[0031] An example of the straight-chain structure is that represented by the following general formula (6). [ka] In the formula, R 7 is as described above, p is a positive number of 1,500 or less, preferably 1 to 1000, more preferably 5 to 500, and even more preferably 10 to 100, q is 0 or a positive number of 300 or less, preferably 1 to 100, and more preferably 5 to 60, and r is 0, 1, 2, or 3, with the proviso that q and r are numbers that satisfy q+2×r≧2.
[0032] Examples of branched structures include R 7 SiO 3 / 2Examples of the branched units include those represented by the following general formula (7). [ka] In the formula, R 7 is as described above, s is a positive number of 1,500 or less, preferably 1 to 1000, more preferably 5 to 500, and even more preferably 10 to 100, t is 0 or a positive number of 300 or less, preferably 1 to 100, and more preferably 5 to 60, u is a positive number of 1 to 10, and v is 0, 1, 2, or 3, with the proviso that t and v are numbers that satisfy t+v≧1.
[0033] SiO 4 / 2 An example of a structure branched by units is one represented by the following general formula (8). [ka] In the formula, R 7 is as described above, w is a positive number of 1,500 or less, preferably 1 to 1000, more preferably 5 to 500, and even more preferably 10 to 100, x is 0 or a positive number of 300 or less, preferably 1 to 100, and more preferably 5 to 60, y is a positive number of 1 to 5, and z is 0, 1, 2, or 3, with the proviso that x and z are numbers that satisfy x+z≧1.
[0034] Also included are those represented by the following formula (9) and having two or more hydrogen atoms bonded to silicon atoms per molecule. [R 7 3SiO 1 / 2 ] a1 [H(R 7 )2SiO 1 / 2 ] b1 [SiO 4 / 2 ] c1 [(OR 8 )SiO 3 / 2 ] d1 (9) In the formula, R 7 is the same as above, and R 8represents a hydrogen atom or an unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, a1 is 0 or a positive number, b1 is a positive number, c1 is a positive number, and d1 is 0 or a positive number. The upper limit for a1, b1, c1, and d1 is each 20.
[0035] A curable liquid silicone composition is obtained by mixing and dissolving a diorganopolysiloxane (A-1) having two or more alkenyl groups per molecule, an organopolysiloxane resin (A-2) having an alkenyl group, and an organohydrogenpolysiloxane (A-3) having two or more SiH groups per molecule.
[0036] The curable liquid silicone composition is composed of 1.0 to 65 parts by mass of the (A-2) component per 100 parts by mass of the total of the (A-1), (A-2) and (A-3) components. If the (A-2) component is less than 1.0 part by mass, the elongation and strength of the silicone rubber will be low. If it is more than 65 parts by mass, the viscosity of the liquid silicone composition will be high, making the emulsification described below difficult. It is preferably 2.0 to 55 parts by mass, more preferably 4.0 to 45 parts by mass.
[0037] The curable liquid silicone composition is preferably one in which the ratio of the number of SiH groups in component (A-3) to the total number of alkenyl groups in component (A-1) and component (A-2) is 0.9 to 3.0. If the ratio of the number of SiH groups in component (A-3) is less than 0.9, the elongation and strength of the silicone rubber will be reduced. If it is more than 3.0, there is a risk of the dispersed particles coagulating in the aqueous dispersion of silicone rubber particles described below. The range of 1.0 to 2.3 is more preferable.
[0038] The silicone rubber of the silicone rubber particles (A) is an addition reaction product of the above-mentioned curable liquid silicone composition. It is preferable to use a catalyst for the addition reaction. Examples of the catalyst for the addition reaction include platinum group metal catalysts used in hydrosilylation reactions. For example, platinum group metals such as platinum (including platinum black), rhodium, and palladium; platinum chlorides such as H2PtCl4·XH2O, H2PtCl6·XH2O, NaHPtCl6·XH2O, KHPtCl6·XH2O, Na2PtCl6·XH2O, K2PtCl4·XH2O, PtCl4·XH2O, PtCl2, Na2HPtCl4·XH2O (wherein X is an integer of 0 to 6, preferably 0 or 6), chloroplatinic acid, and platinum chlorides. Examples of such catalysts include acid salts, alcohol-modified chloroplatinic acid, platinum chloride, complexes of chloroplatinic acid and olefins, complexes of chloroplatinic acid and vinyl group-containing siloxanes, complexes of platinum and vinyl group-containing siloxanes, platinum black, platinum group metals such as palladium supported on supports such as alumina, silica, and carbon, rhodium-olefin complexes, and chlorotris(triphenylphosphine)rhodium (Wilkinson's catalyst). These catalysts may be used alone or in combination of two or more.
[0039] The amount of platinum group metal catalyst to be added may be an effective amount as an addition reaction catalyst, and the amount of platinum group metal in the platinum group metal catalyst relative to the total amount of components (A-1), (A-2) and (A-3) is usually about 0.1 to 500 ppm, preferably about 0.5 to 200 ppm, and more preferably about 1 to 100 ppm, calculated by mass. The addition reaction curing conditions of the curable liquid silicone composition are not particularly limited, but are preferably at a temperature of 1 to 100°C for 1 hour or more. The temperature is preferably 10°C to 100°C.
[0040] The silicone rubber of the silicone rubber particles (A) preferably has an elongation at break of 20% or more and a tensile strength at break of 1.0 MPa or more. The elongation at break and the tensile strength at break refer to values measured by the test method specified in JIS K 6251:2017 for a dumbbell-shaped No. 3 test piece having a thickness of 1 mm, which was heat-treated at 150 ° C for 30 minutes. More preferably, the elongation at break is 50% or more and the tensile strength at break is 2.0 MPa or more. The upper limit of the elongation at break is not particularly limited, but it may be 1000% or less, and in particular 500% or less. The upper limit of the tensile strength at break is not particularly limited, but it may be 20 MPa or less, and in particular 10 MPa or less.
[0041] The silicone rubber of the silicone rubber particles (A) preferably has a type A durometer hardness in the range of 20 to 95. The hardness refers to a value measured by the test method specified in JIS K 6253:2012 for a test piece treated at 150°C for 30 minutes. It is more preferably in the range of 40 to 85.
[0042] The silicone rubber may contain silicone oil, organosilane, inorganic powder, organic powder, antioxidant, and the like.
[0043] [Water dispersion of silicone rubber particles] The aqueous dispersion of silicone rubber particles of the present invention has a composition containing (A) silicone rubber particles, (B) a surfactant, and (C) water.
[0044] The surfactant (B) functions as a dispersant for the silicone rubber particles and, as described below, also functions as an emulsifier for the curable liquid silicone composition in the production of an aqueous dispersion of the silicone rubber particles.
[0045] The surfactant (B) is not particularly limited, and may be a nonionic surfactant, an anionic surfactant, a cationic surfactant, or an amphoteric surfactant. Preferably, it is a nonionic surfactant or an anionic surfactant. These may be used alone or in combination of two or more.
[0046] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyethylene glycol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, propylene glycol fatty acid esters, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene hydrogenated castor oil fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, polyoxyethylene modified organopolysiloxanes, and polyoxyethylene polyoxypropylene modified organopolysiloxanes. Preferably, it is a polyoxyethylene alkyl ether or polyoxyethylene polyoxypropylene alkyl ether having an HLB value of 12.0 to 19.0. More preferably, it is a polyoxyethylene alkyl ether or polyoxyethylene polyoxypropylene alkyl ether having an alkyl group with a carbon number of 10 to 18. Furthermore, the HLB value is more preferably 13.0 to 18.0. The HLB value here is calculated using the following formula: HLB = [molecular weight of polyoxyethylene portion and alcohol portion / molecular weight of surfactant] x 20 When two or more nonionic surfactants with different HLB values are used in combination, the above HLB value is a weighted average value.
[0047] Examples of anionic surfactants include alkyl sulfate salts such as sodium lauryl sulfate, polyoxyethylene alkyl ether sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, sulfate salts of fatty acid alkylolamides, alkyl benzene sulfonates, polyoxyethylene alkyl phenyl ether sulfonates, α-olefin sulfonates, α-sulfofatty acid ester salts, alkyl naphthalene sulfonates, alkyl diphenyl ether disulfonates, alkanesulfonates, N-acyltaurate salts, dialkyl sulfosuccinates, monoalkyl sulfosuccinates, polyoxyethylene alkyl ether sulfosuccinates, fatty acid salts, polyoxyethylene alkyl ether carboxylates, N-acyl amino acid salts, monoalkyl phosphate salts, dialkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, and the like. Preferred are alkyl sulfates having an alkyl group with 10 to 18 carbon atoms, polyoxyethylene alkyl ether sulfates, sulfates of fatty acid alkylolamides, alkylbenzene sulfonates, α-sulfofatty acid esters, alkanesulfonates, N-acyltaurates, polyoxyethylene alkyl ether sulfosuccinates, polyoxyethylene alkyl ether carboxylates, N-acylamino acid salts, monoalkyl phosphates, dialkyl phosphates, polyoxyethylene alkyl ether phosphates, α-olefin sulfonates having an olefin with 10 to 18 carbon atoms, alkylnaphthalene sulfonates having an alkyl group with 1 to 14 carbon atoms, and alkyldiphenyl ether disulfonates having an alkyl group with 6 to 14 carbon atoms.
[0048] Examples of the cationic surfactant include alkyltrimethylammonium salts, dialkyldimethylammonium salts, polyoxyethylenealkyldimethylammonium salts, dipolyoxyethylenealkylmethylammonium salts, tripolyoxyethylenealkylammonium salts, alkylbenzyldimethylammonium salts, alkylpyridinium salts, monoalkylamine salts, and monoalkylamidoamine salts. Examples of the amphoteric surfactant include alkyl dimethylamine oxide, alkyl dimethyl carboxybetaine, alkyl amidopropyl dimethyl carboxybetaine, alkyl hydroxysulfobetaine, and alkyl carboxymethyl hydroxyethyl imidazolinium betaine.
[0049] The amount of component (B) is 0.05 to 20 parts by mass relative to 100 parts by mass of silicone rubber particles (A). If it is less than 0.05 parts by mass, the curable liquid silicone composition described below cannot be emulsified, and the stability of the water dispersion may decrease. If it is more than 20 parts by mass, the water dispersion performance of the silicone rubber particles will not be improved, and the properties of materials such as paints to be mixed may be impaired. It is preferably 0.10 to 10 parts by mass, and more preferably 0.20 to 2 parts by mass.
[0050] Water (C) is a dispersion medium for the silicone rubber particles (A). The amount of component (C) is 20 to 2,000 parts by mass, and preferably 40 to 1,000 parts by mass, per 100 parts by mass of the silicone rubber particles (A).
[0051] If necessary, preservatives, thickeners, pH adjusters, antifoaming agents, etc. may be appropriately blended into the aqueous dispersion of silicone rubber particles.
[0052] [Water dispersion of silicone rubber particles and method for producing silicone rubber particles] The water dispersion of silicone rubber particles can be produced by known methods, such as adding a surfactant (B) and water (C) to a curable liquid silicone composition consisting of components (A-1), (A-2) and (A-3), emulsifying the composition to form an emulsion, and then adding a platinum group metal catalyst to carry out an addition reaction.
[0053] For emulsification, a general emulsifying disperser may be used, and examples of such machines include a high-speed rotating centrifugal radiation type agitator such as a homodisper, a high-speed rotating shear type agitator such as a homomixer, a high-pressure jet type emulsifying disperser such as a homogenizer, a colloid mill, an ultrasonic emulsifying machine, etc. The stirring speed, time, etc. are not particularly limited as long as the emulsification can be performed and the desired particle size can be obtained.
[0054] After preparing emulsion, platinum group metal catalyst is added, but when dispersibility in water is poor, it is preferable to add it to emulsion in a state dissolved in surfactant.As surfactant, the above-mentioned ones can be mentioned, and nonionic surfactant is particularly preferable.It is also possible to mix platinum group metal catalyst in advance with curable liquid silicone composition, but in this case, it is necessary to prevent reaction from proceeding before emulsification is completed by adjusting temperature, adjusting catalyst amount, mixing reaction adjuster, etc.
[0055] The addition reaction may be carried out at room temperature (1 to 30° C.), but in order to increase the reaction rate or the reaction ratio, it may be carried out under heating at less than 100° C. The addition reaction time is appropriately selected.
[0056] The silicone rubber particles can be obtained by removing water (C) from the aqueous dispersion of silicone rubber particles obtained in the above step.
[0057] The water (C) can be removed, for example, by heating the aqueous dispersion under normal pressure or reduced pressure to volatilize it. For example, the method of removing the water by leaving the dispersion liquid stationary under heating, the method of removing the water by stirring and flowing the dispersion liquid under heating, the method of spraying and dispersing the dispersion liquid in a hot air current as in a spray dryer, the method of using a flowing heat medium, etc. can be mentioned. As a pretreatment for this operation, the particles can be aggregated by adding an inorganic salt or the like, and then concentrated by a method such as filtration separation by pressure filtration, centrifugation, decantation, etc., and further, if necessary, the concentrate can be washed with water, alcohol, etc.
[0058] When silicone rubber particles contain silicone oil, organosilane, inorganic powder, organic powder, antioxidant, etc., these may be dissolved or dispersed in the curable liquid silicone composition.
[0059] The silicone rubber particle water dispersion or silicone rubber particles of the present invention are used by being blended into, for example, paints or coating agents. After the paint or coating agent containing the silicone rubber particles is applied to a substrate, it is preferable to heat treat the substrate at a temperature of 100 to 300°C for 1 minute to 3 hours. The heat treatment improves the addition reaction rate and increases the elongation and strength of the silicone rubber. The silicone rubber particles may also be heat treated in advance at a temperature of 100 to 300°C for 1 minute to 3 hours before being blended into a paint or coating agent. EXAMPLES
[0060] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the examples, the kinetic viscosity is a value measured at 25°C using a capillary viscometer.
[0061] The following polysiloxanes were prepared: (A-1)-1: Formula (10), vinyl group amount 0.00627 mol / 100 g, kinetic viscosity 5,060 mm 2 / s vinyl group-containing dimethylpolysiloxane [ka]
[0062] (A-1)-2: Formula (11), vinyl group amount 0.00369 mol / 100 g, kinetic viscosity 30,500 mm 2 / s vinyl group-containing dimethylpolysiloxane [ka]
[0063] (A-1)-3: Represented by formula (12), vinyl group amount is 0.0179 mol / 100 g, kinetic viscosity is 386 mm 2 / s vinyl group-containing dimethylpolysiloxane [ka]
[0064] (A-1)-4: A solution of (A-1)-1 and (A-1)-3 mixed in a mass ratio of 40:60. The vinyl group content is 0.0132 mol / 100 g and the kinetic viscosity is 1080 mm 2 / s vinyl group-containing dimethylpolysiloxane
[0065] (A-1)-5: Formula (13), vinyl group amount 0.120 mol / 100 g, kinetic viscosity 23 mm 2 / s vinyl group-containing dimethylpolysiloxane (for comparison) [ka]
[0066] (A-1)-6: Formula (14), vinyl group amount 0.0348 mol / 100 g, kinetic viscosity 125 mm 2 / s vinyl group-containing dimethylpolysiloxane (for comparison) [ka]
[0067] (A-1)-7: Represented by formula (15), vinyl group amount is 0.0433 mol / 100 g, kinetic viscosity is 378 mm 2 / s vinyl group-containing dimethylpolysiloxane (for comparison) [ka]
[0068] (A-2)-1:(CH3)3SiO 1 / 2 Unit: (CH3)2(CH=CH2)SiO 1 / 2 Units, SiO4 / 2 Units: (OH)SiO 3 / 2 Units, and (OCH3)SiO 3 / 2 A vinyl group-containing methylpolysiloxane resin consisting of the following units and having the following molar ratio: Molar ratio ([(CH3)3SiO 1 / 2 ]+[(CH3)2(CH=CH2)SiO1 / 2 ]) / [SiO 4 / 2 ] is 0.83, Molar ratio [(CH3)3SiO 1 / 2 ] / [SiO 4 / 2 ] is 0.71, Molar ratio [(CH3)2(CH=CH2)SiO 1 / 2 ] / [SiO 4 / 2 ] is 0.1 2, Molar ratio ([HOSiO 3 / 2 ]+[CH3OSiO 3 / 2 ] / [SiO 4 / 2 ]) is 0.088, Molar ratio [HOSiO 3 / 2 ] / [SiO 4 / 2 ] is 0.041, Molar ratio [CH3OSiO 3 / 2 ] / [SiO 4 / 2 ] is 0.047, The vinyl group amount is 0.089 mol / 100 g, and the weight average molecular weight is 4,100.
[0069] (A-2)-2:(CH3)3SiO 1 / 2 Unit: (CH=CH2)3SiO 1 / 2 Units, SiO 4 / 2 Units, HOSiO 3 / 2 Units, and C2H5OSiO 3 / 2 A vinyl group-containing methylpolysiloxane resin consisting of the following units and having the following molar ratio: Molar ratio ([(CH3)3SiO 1 / 2 ]+[(CH=CH2)3SiO 1 / 2 ]) / [SiO 4 / 2 ] is 1.01, Molar ratio [(CH3)3SiO 1 / 2 ] / [SiO 4 / 2 ] is 0.90, Molar ratio [(CH=CH2)3SiO1 / 2 ] / [SiO 4 / 2 ] is 0.11, Molar ratio ([HOSiO 3 / 2 ]+[C2H5OSiO 3 / 2 ] / [SiO 4 / 2 ]) is 0.10, Molar ratio [HOSiO 3 / 2 ] / [SiO 4 / 2 ] is 0.050, Molar ratio [C2H5OsSiO 3 / 2 ] / [SiO 4 / 2 ] is 0.050, The vinyl group amount is 0.23 mol / 100 g, and the weight average molecular weight is 5,730.
[0070] (A-3)-1: Formula (16), SiH group amount is 0.418 mol / 100 g, kinetic viscosity is 27 mm 2 / s Methylhydrogenpolysiloxane [ka]
[0071] (A-3)-2: The compound represented by formula (17), having a SiH group content of 0.744 mol / 100 g and a kinetic viscosity of 117 mm 2 / s Methylhydrogenpolysiloxane [ka]
[0072] (A-3)-3: Formula (18), SiH group amount is 0.137 mol / 100 g, kinetic viscosity is 37 mm 2 / s Methylhydrogenpolysiloxane [ka]
[0073] (A-3)-4: The compound represented by formula (19), having a SiH group content of 0.427 mol / 100 g and a kinetic viscosity of 48 mm 2 / s Methylhydrogenpolysiloxane [ka]
[0074] [Example 1] Vinyl-containing dimethylpolysiloxane (A-1)-1, vinyl-containing methylpolysiloxane resin (A-2)-1 and methylhydrogenpolysiloxane (A-3)-1 were mixed and dissolved in a mass ratio of 63.0:27.0:10.0 to prepare a curable liquid silicone composition. The ratio of the number of SiH groups in the methylhydrogenpolysiloxane to the total amount of vinyl groups in the vinyl-containing dimethylpolysiloxane and vinyl groups in the vinyl-containing methylpolysiloxane resin was 1.49.
[0075] In a 1-liter glass beaker, 500.0 g of a curable liquid silicone composition, 2.0 g of polyoxyethylene tridecyl ether (ethylene oxide added moles = 15 moles) and 80.0 g of water were charged, and the mixture was stirred at 6,000 rpm using a homomixer, becoming oil-in-water type and thickening was observed, and stirring was continued for another 15 minutes. Next, 415.6 g of water was added while stirring at 2,000 rpm, and a uniform white emulsion was obtained. This emulsion was transferred to a 1-liter glass flask equipped with a stirrer using an anchor-shaped stirring blade, and after adjusting the temperature to 15 to 20°C, a mixed solution of 1.2 g of an isododecane solution of a platinum-vinyl group-containing disiloxane complex (platinum content 0.5%) and 1.2 g of polyoxyethylene lauryl ether (ethylene oxide added moles = 9 moles) was added while stirring. Stirring was continued at the same temperature for 6 hours, and the curable liquid silicone was cured by addition reaction to obtain an aqueous dispersion of silicone rubber particles. The total amount of polyoxyethylene tridecyl ether and polyoxyethylene lauryl ether was 0.64 parts by mass per 100 parts by mass of the obtained silicone rubber particles.
[0076] When the shape of these silicone rubber particles was observed under an optical microscope, they were found to be spherical, and when the volume average particle size was measured using a particle size distribution measuring device "Multisizer 3" (product name, manufactured by Beckman Coulter, Inc.), it was found to be 6.7 μm.
[0077] The water was removed by volatilization from the obtained aqueous dispersion of silicone rubber particles using a spray dryer at an inlet temperature of 150°C and an outlet temperature of 80°C to obtain silicone rubber particles. The obtained silicone rubber particles were then heated in a thermostatic chamber at 150°C for 30 minutes.
[0078] The resulting silicone rubber particles were not sticky and were found to be spherical when examined under an electron microscope.
[0079] The tensile strength at break and elongation at break of the silicone rubber of the silicone rubber particles were measured as follows. 100 parts by mass of a curable liquid silicone composition prepared with the same composition as in Example 1 above was mixed with 0.24 parts by mass of an isododecane solution of a platinum-vinyl group-containing disiloxane complex (platinum content 0.5%) and 0.05 parts by mass of 1,1-dimethylpropynyloxytrimethylsilane (reaction regulator), and then poured into a polypropylene tray to a thickness of about 1 mm. After leaving at 25°C for 24 hours, the cured silicone was peeled off from the tray and heated in a thermostatic chamber at 150°C for 30 minutes to obtain a non-sticky silicone rubber sheet. This silicone rubber sheet was cut to the shape and dimensions of a dumbbell-shaped No. 3 test piece specified in JIS K6251: 2017, and the tensile strength at break and elongation at break were measured according to the method specified in JIS K6251: 2017. The tensile strength at break was 6.5 MPa, and the elongation at break was 101%.
[0080] The hardness of the silicone rubber of the silicone rubber particles was measured as follows. 100 parts by mass of the curable liquid silicone composition prepared with the same composition as in Example 1 above was mixed with 0.24 parts by mass of an isododecane solution of platinum-vinyl group-containing disiloxane complex (platinum content 0.5%) and 0.05 parts by mass of 1,1-dimethylpropynyloxytrimethylsilane (reaction regulator), and then poured into an aluminum petri dish to a thickness of 10 mm. After leaving it at 25°C for 24 hours, it was heated in a thermostatic chamber at 150°C for 30 minutes to obtain a non-sticky silicone rubber. The hardness of this silicone rubber was measured with a type A durometer specified in JIS K6253 and was 58.
[0081] [Examples 2 to 11] [Comparative Examples 1 to 10] Example 1 was repeated to obtain an aqueous dispersion of silicone rubber particles, except that a curable liquid silicone composition was used in which a vinyl-containing dimethylpolysiloxane, a vinyl-containing methylpolysiloxane resin (some compositions contained no vinyl) and a methylhydrogenpolysiloxane were mixed and dissolved in the composition shown in Table 1 or 2. The volume average particle size of the silicone rubber particles, the shape of the silicone rubber particles, the tensile strength at break of the silicone rubber, the elongation at break of the silicone rubber, and the hardness of the silicone rubber, which were measured in the same manner as in Example 1, are shown in Tables 1 and 2.
[0082] [Table 1]
[0083] [Table 2]
[0084] [Example 12] Vinyl-containing dimethylpolysiloxane (A-1)-4, vinyl-containing methylpolysiloxane resin (A-2)-1 and methylhydrogenpolysiloxane (A-3)-1 were mixed and dissolved in a mass ratio of 62.0:26.6:11.4 to prepare a curable liquid silicone composition. The composition is the same as that of the curable liquid silicone composition of Example 11. The silicone rubber thus obtained had a tensile strength at break of 3.0 MPa, an elongation at break of 75%, and a type A durometer hardness of 61.
[0085] In a 1-liter glass beaker, 500.0 g of the above-mentioned curable liquid silicone composition, 1.0 g of polyoxyethylene tridecyl ether (ethylene oxide added moles = 15 moles) and 100.0 g of water were charged, and the mixture was stirred at 6,000 rpm using a homomixer, becoming oil-in-water type and thickening was observed, and stirring was continued for another 15 minutes. Next, 396.6 g of water was added while stirring at 2,000 rpm, and a uniform white emulsion was obtained. This emulsion was transferred to a 1-liter glass flask equipped with a stirrer using an anchor-shaped stirring blade, and after adjusting the temperature to 15 to 20°C, a mixed solution of 1.2 g of an isododecane solution of a platinum-vinyl group-containing disiloxane complex (platinum content 0.5%) and 1.2 g of polyoxyethylene lauryl ether (ethylene oxide added moles = 9 moles) was added while stirring. Stirring was continued at the same temperature for 6 hours to obtain an aqueous dispersion of silicone rubber particles.
[0086] The shape of the silicone rubber particles in the water dispersion was observed under an optical microscope and found to be spherical, and the volume average particle size was measured using a particle size distribution analyzer "Multisizer 3" (product name, manufactured by Beckman Coulter, Inc.) and found to be 11 μm. The water in the obtained water dispersion of silicone rubber particles was volatilized and removed using a spray dryer under conditions of an inlet temperature of 150°C and an outlet temperature of 80°C to obtain silicone rubber particles. The obtained silicone rubber particles were then heated in a thermostatic chamber at 150°C for 30 minutes. The obtained silicone rubber particles were not sticky, and their shape was found to be spherical when observed under an electron microscope.
[0087] [Example 13] In a 1-liter glass beaker, 500.0 g of the same curable liquid silicone composition as in Example 12, 6.0 g of polyoxyethylene tridecyl ether (ethylene oxide added moles = 15 moles), and 40.0 g of water were charged, and the mixture was stirred at 6,000 rpm using a homomixer, resulting in an oil-in-water emulsion and thickening. The mixer was then changed to a disperser and stirred at 4,000 rpm for 15 minutes. The mixer was then changed to a homomixer again, and 451.6 g of water was added while stirring at 2,000 rpm, resulting in a uniform white emulsion. This emulsion was transferred to a 1-liter glass flask equipped with an anchor-type stirring blade stirrer, and the temperature was adjusted to 15 to 20°C, after which a mixed solution of 1.2 g of an isododecane solution of a platinum-vinyl group-containing disiloxane complex (platinum content 0.5%) and 1.2 g of polyoxyethylene lauryl ether (ethylene oxide added moles = 9 moles) was added under stirring. The mixture was stirred at the same temperature for 6 hours to obtain an aqueous dispersion of silicone rubber particles.
[0088] The shape of the silicone rubber particles was observed under an optical microscope and found to be spherical, and the volume average particle size was measured using a particle size distribution analyzer "Multisizer 3" (product name, manufactured by Beckman Coulter, Inc.) and found to be 1.9 μm. The water dispersion of the obtained silicone rubber particles was volatilized and removed using a spray dryer under conditions of an inlet temperature of 150°C and an outlet temperature of 80°C to obtain silicone rubber particles. The obtained silicone rubber particles were then heated in a thermostatic chamber at 150°C for 30 minutes. The obtained silicone rubber particles were not sticky, and their shape was found to be spherical when observed under an electron microscope.
[0089] [Example 14] In a 1-liter glass beaker, 500.0 g of the same curable liquid silicone composition as in Example 12, 5.7 g of 35% sodium pentyl naphthalene sulfonate aqueous solution (amount of sodium pentyl naphthalene sulfonate = about 2.0 g), and 76.0 g of water were charged, and the mixture was stirred at 6,000 rpm using a homomixer, becoming an oil-in-water type and thickening was observed. Next, the mixer was changed to a disperser, and the mixture was stirred at 4,000 rpm for 15 minutes. The mixer was again changed to a homomixer, and 415.9 g of water was added while stirring at 2,000 rpm, resulting in a uniform white emulsion. This emulsion was transferred to a 1-liter glass flask equipped with an anchor-type stirring blade stirrer, and after adjusting the temperature to 15-20°C, a mixed solution of 1.2 g of an isododecane solution of platinum-vinyl group-containing disiloxane complex (platinum content 0.5%) and 1.2 g of polyoxyethylene lauryl ether (ethylene oxide added moles = 9 moles) was added while stirring. Stirring was continued at the same temperature for 6 hours to obtain an aqueous dispersion of silicone rubber particles.
[0090] The shape of the silicone rubber particles was observed under an optical microscope and found to be spherical, and the volume average particle size was measured using a particle size distribution analyzer "Multisizer 3" (product name, manufactured by Beckman Coulter, Inc.) and found to be 6.4 μm. The water dispersion of the obtained silicone rubber particles was volatilized and removed using a spray dryer under conditions of an inlet temperature of 150°C and an outlet temperature of 80°C, yielding silicone rubber particles. The obtained silicone rubber particles were then heated for 30 minutes in a thermostatic chamber at 150°C. The obtained silicone rubber particles were not sticky, and their shape was found to be spherical when observed under an electron microscope.
Claims
1. The silicone rubber particles are spherical and have a volume average particle size of 0.5 to 50 μm, and are an addition reaction product of a curable liquid silicone composition comprising the following components (A-1), (A-2) and (A-3): (A-1) a diorganopolysiloxane having two or more alkenyl groups in one molecule, the amount of alkenyl groups being 0.0025 to 0.034 mol / 100 g; (A-2) R １ ３ SiO １／２ Units and SiO ４／２ Contains units, SiO ４／２ R for units １ ３ SiO １／２ an organopolysiloxane resin having a molar ratio of units of 0.60 to 1.7 and an alkenyl group content of 0.001 mol / 100 g or more; (In the above formula, R １ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms without an alkenyl group, or an alkenyl group having 2 to 6 carbon atoms, １ at least one of which is an alkenyl group; and (A-3) Organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms (referred to as SiH groups) per molecule, the amount of SiH groups being 0.030 to 1.30 mol / 100 g. The amount of the component (A-2) is 1.0 to 65 parts by mass per 100 parts by mass of the total of the components (A-1), (A-2) and (A-3).
2. 2. The silicone rubber particles according to claim 1, wherein the silicone rubber particles are made of a silicone rubber having a dumbbell-shaped No. 3 test piece having an elongation at break of 20% or more in a rubber sheet having a thickness of 1 mm and heat-treated at 150° C. for 30 minutes according to the test method specified in JIS K 6251, and a tensile strength at break of 1.0 MPa or more in a test method specified in JIS K 6251.
3. (A) The silicone rubber particles according to claim 1 or 2: 100 parts by mass (B) a surfactant: 0.05 to 20 parts by mass, and (C) Water: 20 to 2,000 parts by mass The aqueous dispersion of silicone rubber particles comprising the above.